Ureido thickened grease

ABSTRACT

Certain properties of lubricant greases prepared by thickening a lubricating oil with a thickener prepared by reacting stoichometric amounts of an abietyl amine and a polyisocyanate are improved by incorporating in such lubricant greases an excess of the polyisocyanate.

Liehe et ai. [4 1 Apr. 1, W72

54] UREHDO THIICKENED GREASE 2,710,840 6/1955 Swakon etal ..2s2/51.5

[72] Inventors: Hubert J. Liehe, Whiting; Wilbur L. Prima ry ExammerDamel E. Wyman Hayne Hammond both of Assistant Examiner-I. Vaughn [73] Assignee: Standard Oil Company, Chicago, Ill. Attorney-Arthur G. Gilkes, William T. McClain and David B. 22 Filed: July 25,1969 [21] Appl.No.: 845,028 [57] ABSTRACT Certain properties of lubricant greases prepared by thickening [52] U.S.Cl ..252/49.6, 252/515 R, 252/51.5A a lubri ting oil with a thickener prepared by reacting [51] lnt.Cl. ..C10m 5/20 s chom ric amounts of an abietyl amine and a polyiso- [58] Field of Search ..252/25,51.5 R,5l.5 A,49.6 cyanate are improved by incorporating in such lubricant greases an excess of the polyisocyanate. [56] References Cited 5 Claims, No Drawings UNITED STATES PATENTS 3,015,625 1/1962 Rosscup et al ..252/51.5

meme THICKENED GREASE BACKGROUND OF THE INVENTION U.S. Pat. No. 3,015,625 issued Jan. 2, 1962, to R. J. Rosscup and H. .l. Liehe, the disclosure of which is incorporated herein by reference, describes and claims lubricant greases prepared by thickening a lubricating oil with a thickener prepared by heating a mixture of an abietyl amine and a polyisocyanate in the equivalent weight ratio of 1:1. Usually the ureido thickened grease contains a slight stoichometric excess of the amine. Greases prepared with such ureido compound thickeners exhibit excellent lubricating properties at elevated temperatures. However, because the cost of preparing such greases may be higher than the cost of preparing greases with other thickeners, it is desirable to find a method of decreasing such cost. One way of accomplishing this would be by improving the yield of a grease product by decreasing the penetration of the grease product for a given thickener content.

SUMMARY In accordance with the present invention, the yield and other properties of lubricant greases prepared with an ureido compound thickener of the general Formula (I) of US. Pat. No. 3,015,625, supra, are improved by incorporating in the finished grease base an excess, in amounts of from about 0.05 percent to about 2 percent, of the stoichometric amount of the polyisocyanate required for the formation of the ureido compound thickener. Preparation of the ureido compound thickener in the presence of excess polyisocyanate will prevent the formation of grease of the proper consistency.

Accordingly, lubricant grease compositions of the present invention comprise a lubricating oil thickened to the desired consistency, i.e., penetration, with from about 2 percent to about 25 percent of at least one ureido compound of the general Formula I, and from about 0.25 percent to about 0.5 percent stoichometric excess of a polyisocyanate as hereinafter defined.

The ureido compound thickeners used in preparing the grease base of the present invention have the general formula HOH H llll l NR (I) where R and R" are the same or different abietyl radicals selected from the group consisting of a dehydroabietyl radical, a dihydroabietyl radical, and tetrahydroabietyl radical and mixtures thereof and R is an alkylene radical or substituted alkylene radical of from one to about 30 carbon atoms or an arylene radical or a substituted arylene radical. The radicals R, R and R" can contain substituents such as, for example, alkyl, alkoxy, cyano, aryl, hydroxy, carboxy, halogen, nitro and other substituent groups. The alkylene radical can be straight and/or branched chain, and the arylene radicals can be mononuclear or polynuclear such as phenylene, biphenylene, naphthylene, anthrylene and phenanthrylene radicals. The terms alkylene and arylene radicals as used herein and in the appended claims include substituted alkylene radicals and substituted arylene radicals.

The general structural formula of the above-named abietyl radicals are:

H C Hz- (5H3 Dehydroabietyl The ureido compound can be prepared by heating a mixture of an abietyl amine such as hereinafter named and a polyisocyanate in the equivalent weight ratio of 1:1, at a temperature within the range of room temperature (about 70 F.) to about 450 F.

The ureido compound thickened grease can be prepared by preforming the ureido compound as described in Example I of US. Pat. No. 3,015,625, supra, incorporating the ureido compound in the oil vehicle, and adding the excess polyisocyanate.

Another method of preparing the grease is to form the ureido compound in situ in the oil vehicle. In the in situ method, the desired amount of the polyisocyanate is placed in a high temperature grease kettle, or other suitable heating equipment, containing a major proportion of the liquid lubricant vehicle to be used and the mixture heated to effect solution. To the heated solution is added the hydroabietylamine and the balance of the oil or a solution of the hydroabietylamine in the balance of the liquid lubricant vehicle and the mixture heated'to a temperature of about 200 F. to 450 F. and maintained at said temperature until the product increases to the desired consistency. The temperature at which the mixture sets-up depends largely upon the nature of the liquid lubricant vehicle employed. When using a hydrocarbon oil such as a petroleum oil the mixture sets-up or reaches the desired consistency when the temperature reaches 350400 F., while when using a synthetic oil, such as a dialkyl ester of a dibasic carboxylic acid, such as di-isooctyl azelate, dialkyl sebacate, etc., the desired consistency is obtained by heating to 220-320 F. After the formation of the ureido compound, the excess amount of the polyisocyanate is then added to the grease mix and the product finished by cooling and milling.

Still another method of making the grease is to first prepare a concentrate of the ureido compound in an oleaginous vehicle, mixing the preformed ureido compound concentrate with the necessary amount of the lubricant vehicle to give a grease product containing the desired amount of the ureido thickener, and then adding the desired amount of excess polyisocyanate. If desired, the excess polyisocyanate may be incorporated in the preformed ureido compound concentrate.

The ureido compound concentrate can be suitably prepared by maintaining a solution of the abietyl amine and an oil, for example a petroleum oil of suitable viscosity, at about F., and a solution of the polyisocyanate and the oil at about 200 F., and combining the two solutions in a spray nozzle and permitting the sprayed droplets of reacting solutions to fall freely in a spray tower. By controlling the rate of flow with respect to the internal volume of the spray nozzle, the reacting solution is discharged before crystallization occurs, and most of the precipitation of the resultant reaction product occurs during the fall through the spray tower. The precipitated droplets are suitably collected in shallow pans at the bottom of the spray tower and the collected material permitted to cool to ambient room temperature in a quiescent state. Concentrates of from about 25 percent to about 60 percent of the ureido compound in oil can be prepared by the above method, although obviously the method is equally suitable for the preparation of smaller or larger amounts of the ureido compound in oils. The so-called spray technic above described, is described and claimed in US. Pat. No. 2,925,387, to T. Traise et al., which is incorporated herein by reference.

Lubricating greases can be readily prepared with the above described ureido concentrates by charging the ureido concentrate to a mixing kettle, adding a portion of the oil vehicle thereto, while stirring and raising the temperature to about 200 to 250 F., preferably about 200 F. At this temperature, the remaining portion of the oil vehicle required to bring the grease to the final desired thickener concentration is added, and the temperature of the mix raised to about 350 to 410 F preferably about 385 F., at which temperature it is held for about to 60 minutes, preferably about 30 minutes. The grease is then cooled to about 175 to 300 F., preferably about 200 F., the excess amount of the polyisocyanate added, and such additives as desired then incorporated in the product. The grease is then passed through a colloid mill and packaged.

Examples of abietyl amines, i.e., aliphatic amines attached to an alicyclic structure, which can be used in the preparation of the above described ureido compounds are dehydroabietyl amine, dihydroabietyl amine and tetrahydroabietyl amine or mixtures of such amines. A particularly well suited amine is a product marketed by Hercules Powder Company as Amine 750. This product is prepared by the catalytic hydrogenation of Rosin Nitrile D prepared by the action at elevated temperatures of ammonia on hydrogenated rosin. Distilled and undistilled grades are available as Amine 750 and Amine 751." The Amine 750 is a mixture of abietyl amines as follows:

Dehydroabietyl amine Dihydroabietyl amine Tetrahydroabietyl amine The polyisocyanate used may be an aliphatic or an aromatic polyisocyanate. Examples of suitable polyisocyanates are tolylene diisocyanate; p,p-diisocyanate biphenyl; 1,4-diisocyanato-benzene; p,p-diisocyanato-diphenylmethane; 1,6- diisocyanoto-hexane; 1,1 Z-diisocyanotododecane 1,3,5- benzene-triisocyanate; naphthylene diisocyanate; bitolylene diisocyanate; tris-p-isocyanato-phenylmethane; etc.

Oleaginous lubricant vehicles which can be thickened with the herein described polyureido compounds to form greases of the present invention can be silicone polymer oils, mineral lubricating oils, synthetic hydrocarbon lubricating oils, synthetic lubricating oils such as polyalkylene glycols and their derivatives, high molecular weight esters of dicarboxylic acids, polyfluoro derivatives of organic compounds such as the trifluorovinyl chloride polymers known as Fluorolube (made by Hooker Chemical Company) and the trifluorochloroethylene polymers, known as example, l(el-F0" (made by The M. W. Kellogg Company), and other lubricant vehicles.

Other oleaginous vehicles which may be employed are, for example, mineral oils in the lubricating oil viscosity range, i.e., from about 50 S.S.U. at 100 F. to about 300 S.S.U. at 210 F. These mineral oils may be suitably solvent extracted, with phenol, furfural, B,B'-dichlorodiethyl-ether (Chlorex), liquid S0 nitrobenzene, etc. Synthetic lubricating oils resulting from polymerization of unsaturated hydrocarbons or other oleaginous materials within the lubricating oil viscosity range such as high molecular weight polyoxyalkylene compounds such as polyalkylene glycols and esters thereof, aliphatic diestcrs of dicarboxylic acids such as the butyl, hexyl, 2-ethylhexyl, decyl, lauryl, etc., esters of sebacic acid, adipic acid, azeleic acid, etc., may be thickened by the ureido compounds of the present invention to produce excellent greases. Polyfluoro derivatives of organic compounds, particularly hydrocarbons and dibasic acid esters of l-1(CF ),,CH OH, in the lubricating oil viscosity range can be thickened with compounds of the present invention. Other synthetic oils, such as esters of aliphatic carboxylic acids and polyhydric alcohol, e.g. trimethylolpropane pelargonate, pentaerythritol hexanoate, can be used as suitable oil vehicles.

PREFERRED EMBODIMENT The following examples are illustrative of a preferred embodiment of the present invention.

EXAMPLE I An ureido compound thickened grease employing Amine 750" and bitolylene diisocyanate was prepared as follows:

a. To a grease kettle were added 1,400 gallons of a SAE 10 solvent-extracted base petroleum oil and 262 pounds of bitolylene diisocyanate, the mixture heated to F., and after shutting off the heat the mixture stirred for about one-half hour to dissolve the isocyanate.

. The oil solution of the isocyanate is then heated to 210 F. and 660 pounds of Amine 750 rapidly added to the heated oil solution, and the mixture heated to 385 F. with medium stirring. At 385 F., the heat source is removed, and when the temperature of the batch reaches 390 F. the heated mixture is transferred to a mixer while stirring at low speed. After transfer to the mixer, the transfer line is flushed with 20 gallons of solvent-treated SAE 10 base oil.

The solution in the mixer was cooled to 225 F. and the following additives, 36 pounds of an aromatic amine antioxidant (marketed as Ortholeum 300"), 180 pounds of zinc naphthenate, 180 pounds of tricresyl phosphate, and 180 pounds of an EP agent (marketed as Santopoid 23R1speed for one-half hour, and then milled.

d. The grease was adjusted to the desired consistency by grading in solvent-extracted SAE 10 base oil. The thickener concentration was 6.0 percent.

EXAMPLE IA The grease of Example 1A was prepared as the grease of Example 1 except that 0.4 percent (based on the finished grease) of added bitolylene diisocyanate was incorporated along with the additives in step (c). The thickener concentration in this grease was 5.2 percent.

EXAMPLE [8 The grease of this Example was prepared as the grease of Example IA, except that 0.47 percent bitolylene diisocyanate was incorporated. The thickener concentration of the sample was 5.2 percent.

EXAMPLE II The grease of this Example was prepared as the grease of Example I except that the grease contained no tricresyl phosphate.

EXAMPLE A The grease of this Example was prepared as the grease of Example 11, except that 0.1 percent added bitolylene diisocyanate was incorporated along with the additives in step (c).

EXAMPLE [1B The grease of this Example was prepared as the grease of Example 11A, but contained 0.2 percent added bitolylene diisocyanate.

EXAMPLE 11C The grease of this Example was prepared as the grease of Example A, but contained 0.4 percent added bitolylene diisocyanate.

EXAMPLE in The grease of this Example was prepared as the grease of Example ll.

EXAMPLE 111A The grease of this Example was prepared as the grease of Example ill, but contained 0.4 percent added bitolylene diisocyanate.

The effectiveness of the present invention in improving the yield and properties of ureido compound thickened grease is demonstrated by the data in Table 1.

TABLE I Percent 212 F. AS'IM added oven ASTM drop point bitolyl- Worked leakage drop F. alter ene dilsopenetrate point, 400 F. heat Sample No. cyanate tion 1 percent 2 F treatment 1 ASTM penetration after being Worked 60 strokes.

2 Sixty mesh screen in the shape of a cone is loaded with grams of the grease, and the cone supported in beaker is placed in a 212 F. oven for 24 hours. Oil leakage from the grease collected in the beaker is weighed and the percent oil loss from the grease calculated.

Examples III and IIIA demonstrate that the addition of excess polyisocyanate, e.g., bitolylene diisocyanate, imparts a more stable drop point to ureido compound thickened greases.

The percentages given herein and in the appended claims are weight percentages, unless otherwise stated.

Although the present invention has been described in the reference to specific embodiments thereof, the invention is not limited thereto, but includes within its scope such modifications and variations as come within the scope of the appended claims.

We claim:

I. An improvement in a lubricating grease comprising a normally liquid lubricant vehicle thickened with from about 2 percent to about 25 percent, by weight, of at least one ureido compound having the general formula wherein R and R" are abietyl radicals selected from the group consisting of a dehydroabietyl radical, a dihydroabietyl radical, a tetrahydroabietyl radical and mixtures thereof, and R is an organic radical selected from the group consisting of an alkylene radical of from one to about 30 carbon atoms and an arylene radical, wherein the improvement comprises the incorporation in said grease of an added amount of from about 0.05 percent to about 2.0 percent of the weight of said grease of a polyisocyanate selected from the group consisting of an aliphatic polyisocyanate and an aromatic polyisocyanate.

2. The composition of claim 1 wherein said vehicle is a hydrocarbon lubricating oil.

3. The composition of claim 1 wherein said vehicle is an acyclic ester of an aliphatic dicarboxylic acid.

4. The composition of claim 1 wherein said vehicle is a silicone lymer oil in the lubriqatinlg oil viscosity range.

5. he composition of claim wherein R is a brtolylene radical, and said polyisocyanate is bitolylene diisocyanate. 

2. The composition of claim 1 wherein said vehicle is a hydrocarbon lubricating oil.
 3. The composition of claim 1 wherein said vehicle is an acyclic ester of an aliphatic dicarboxylic acid.
 4. The composition of claim 1 wherein said vehicle is a silicone polymer oil in the lubricating oil viscosity range.
 5. The composition of claim 1 wherein R'' is a bitolylene radical, and said polyisocyanate is bitolylene diisocyanate. 